This invention relates to the reduction of contaminant levels in gases and liquids, and, more particularly, to the use of a low-energy electron beam to destroy contaminant compounds.
A variety of contaminants, sometimes also termed pollutants, are sometimes present in air and water at levels in the parts per million range. These contaminants include various active and inert organic compounds as well as inorganic compounds such as the nitrogen oxides termed NO.sub.x and the sulfur oxides termed SO.sub.x. In some instances these contaminants have been proved harmful to life, crops, and buildings, and in other instances it is desirable to remove them from the environment for aesthetic reasons.
A wide variety of chemical and energetic techniques have been developed to reduce the levels of specific contaminant compounds. The chemical reaction techniques often themselves involve the use or production of other harmful substances. Typical destruction techniques generally involve exposing the contaminant to some type of energetic environment to modify the contaminant in some fashion.
In one approach, a high-energy beam of electrons is directed through a fluid containing a contaminant. The electron beam, having electrons with energies of about 0.3 to about 8 million electron volts (Mev), reduces the concentration of contaminants in the fluid. The reduction mechanism is thought to involve breaking of the internal chemical bonds of the contaminants to modify them to a less noxious form.
The present inventors have observed that the use of such high-energy electron beams has the significant drawback that extensive shielding of any decontamination apparatus is required. The high-energy electron beam is injurious to life, as are the Bremstrahlung and X-radiation that may be produced in such an apparatus. Consequently, such an apparatus must be large and bulky, because extensive shielding is required. The shielding also adds significantly to the cost of the apparatus, and limits its use in some situations of interest.
There is therefore a need for an improved approach for reducing contaminant levels in fluids. The present invention fulfills this need, and further provides related advantages.